[VBprogrammer]

If instead of buying the house cash I put it all into bitcoin at the begining of the year I'd now have enough to pay off the mortgage, the early repayment fee and have change to spare.

This being the utter fucking fallacy of hypothesising with the benefit of perfect information.

[grey-area]

Personally I wouldn't touch bitcoin, nor do I consider it an asset. Returns on stock investments are historically high for the last couple of decades it's true, but if you take the average of say 5% a year, it's still much better than putting that money into a mortgage, when you can borrow the money over a long time period at < 1% (as in the UK for example), or even at 3%.

It's not a trick, it's simple maths. It certainly doesn't always work, and there are risks involved, so not everyone will agree on the right decision, but there is clearly a path where borrowing money to pay for a large asset makes sense.

[VBprogrammer]

You've basically just reinvented the endowment mortgage. That went really well for everyone in the 90s.

[grey-area]

No. I wasn't suggesting investing to pay off the mortgage (endowment mortgage), but investing as an alternative use of funds compared to paying off a debt held at low interest rates in a rapidly depreciating currency.

Imagine a more extreme example:

Interest rates 0.1%, Inflation 10%, 30 year term, leverage meaning your 50k becomes say 500k invested.

Now it makes sense to take on as much debt as you can get over say 30 years, and to put off paying it as long as possible, because even after a few years the payments will be quite minor compared to your inflating income, and at the end of the 30 years the debt you have left and the interest payments on it will be trivial compared to your income.